Fuse



Patented Apr. 22, 18924.

`UNITI-:D STAT-Es 1,491,695 PATENT' ori-fica. v

ARCHBALD GRTEVE, OF WESTPORT, CONNECTICUT, ASSIGNOR TO' CHARLES H.KEMPER, INC., OF WES'ITORT, CONNECTICUT, A CORPORATION OF CONNECTICUT.

'rusia n Y Application tied February 4, 1921. Serial No. 442,516.

To all whom it may concern.'

Be it known that I, ARCHIBALD GRIEVE, a subject of the King of GreatBritain, residing at Westport, in the county of Fairfield and State ofConnecticut, have invented certain new and useful Improvements in Fuses,of which the following is a specification. i My invention relates toelectric fuses, and l particularly' to renewable cartridge fusesof theclip type. Among the objects of my invention may be particularlymentioned-- one, the provision of a construction in which a rated endofthe fusestrip may be carried with safety te `exposed position on theinterior of the fuse casing; two, an end construction in which there isbut a single dey tachable member; three, aconstruction using a draw-upscrew ferrule having means to prevent the escape of gases to thethreaded area of the ferrule and its complementary part of the fusecasing; four, an end lconstruction in which a circuitous gas escapepassa is. provided by the detachable ferrule e ement; five, a contactmember freely vcarried by the end ferrule to lengage the bent-over endof the fuse strip, but having a swiveling connection with the ferrule soas to protect the fuse strip end "against, which it bears -from ruturing strains, and

at the same time aifor ing by its loose engagement with the ferrule agas vent; six, various details of improved constructionhereinafter'pointed oit or shown in the accompanying drawings2 in which-Fi 1 is a broken side elevation of a fuse in w ich my invention isembodied infone form, the end cap at the left-hand end of the fuse beingshown detached' Figs. 2, 3 and 4 are dend elevation and sections,respectively, on the lines 2 2, 3-3 and 4-4,` Fig. 1; and

. Fig.. 5 is a longitudinal section at right lan les to Fig. 1.

n certain res ects the present construction is akin to t at illustratedin my application Ser. No. 442,515 filed herewith on the blade t fuse,although, like man is susceptib e of modification in various pari 5ticulars, whilestill retaining the underlyin features to which .theinvention is directe Asillustratively embodied in the construc- .tionshown in the accompanying drawing, the fuse comprises a tubular -casin 6of liber, or other insulating material, avingis thus sufficientmechanical strength to withstand the strains imposed upon it on theblowing of the fuse.` At the opposite ends of the casing are metalbushings 7 and 8 having reduced lnecks, which are forced into the endsof the casing and riveted thereto at 9. These necks are `preferablyexternally serrated, notonly to grip the fiber casing me-v chanically,but also to prevent the escape vof gas through the joint, to the injuryof the fiber, on the blowing ofthe fuse strip'.l Adjacent the shoulder10 of the bushing, which abuts against the end of the casing 6, thebushing is threaded. at 11 to receive the detachable ferrule 12.

The slightly reduced cylindrical outer ends yof the bushing are providedwith closure diaphragms 13 and 14, on which at 15 and .16, respectivelylare pivoted shutters 17 and 18. The latter substantialll close the endopenings 19 in the diap ragms 13 and 14,'-through which the oppositeendsv vof thefuse strip 20 are passed to the exterior of the bushings.As will be noted from Figs. 2 and 3, the :portion of the shutter 80voverlying the opening 19 isprovided with a straight edge 21, which inadjusted position, determined by the stud X, lies parallel to one edgeof the opening 19, but spaced slightly therefrom to afford a narrow exitplassage y22', which is substantially filled e 'fuse strip as it passesout therethrough from the yfuse chamber. The shutterfis preferablysoshaped that. its margin 23dconforms to the contour of the bushing en Inorder to afford a suitable contact area,

vthe projecting ends of the fuse strip are angled over the straight edes 21 of the shutters and overlie .the outer aces of the latter. At oneend of the fuse the shutter is' notched at 24 tolpermit an extension 25of the fuse strip to be turnedA back therethrough between the skirt ofthe ferrule 12 and the outer -face of the bushin i7, in which a lshallowgroove 26 is forme in re ister with a continuation 27 thereof in the secasing to receive the'end of the fuse strip. The latter bears a ratinindication 28, which exposed on 't e exterior Aofthe fuse casing beyondthe edge of the yskirtof the ferrule 12, and is readily observed by an finspector. v v To prevent escapejof gases through the groove 26, 27,thelatter is of such width 110 not actually seal the passageway.Furthermore, the fit of the reduced end of the bushing with the innertace of the skirt of the ferrule is as snug as possible, and may bereadily made so tight that the escape of gas to the threaded area of thebushing and ferrule is rendered practically impossible.

It will be noted that the gases escape from the fuse chamberprincipally, if not entirely, at the narrow passage 22, through whichthe fuse strip emerges and thus has a restricted entry into theexpansion chamber 30 formed between the end of the bushings and the endof the ferrule. i From this chamber 30, in which the gases are cooled byexpansion, they escape through a circuitous passage in contact withmetallic cooling surfaces. To effect this, on the closed end of theferrule 12 is mounted a gas deliecting washer 32 of slightly lessdiameter than the internal diameter of the cap. On the outer face of thelwasher are formed channels 33, or other venting passageways, which leadto a central-orifice 34 in the end of the ferrule. not completely,obstructed by the retaining stud 35 on the washer, which passes throughthe orifice and is sufficiently headed up to secure the washer to theferrule end while nevertheless affording the play in the orificenecessary to permit the latter to functionas a gas escape passage. Thisstud may be integral with the washer, as indicated, or it may be anindependent member passing therethrough and riveted in position by asuitable spreading operation. Preferably associated withthe washer is aninner bearing boss 36 which overlies and contacts with the bent-over endof the fuse strip when the ferrule is screwed down on the bushing.

Obviously, the loose attachment of the washer to the end of the cappermits the boss 36 to remain stationary in swiveling engagement withthe ferrule as the latter is screwed home on the bushing. This ventsinjury by the boss to the fusestrip end which might otherwise be torn orruptured during the screwing down of the ferrule were the washers forcedto rotate with the ferrule.

Inassembled position the ferrules 12 are screwed down hard upon the endbushings 7 and 8, thus not only establishing good electrical contactwith the bent-over ends of the fuse strips, but also firmly pressing theshutters 17 and 18 against the end diaphragms 13 and 14 of the bushingsand positioning the skirt of the ferrule in engagemeut-with the reducedend ofthe bush- This orifice is largely, but

pre-

ing. This renders the closure of the fuse chamber complete, except forthe restricted openings between the shutters and the diaphragms at thepoints at which the ends of the fuse strip pass out of the fuse chamber.On the blowing of the fuse, the gases emerge through this passage totheexpansion chamber 30, where they are cooled by expansion 'and reduced inpressure. From the expansion `chamber the Vgases are constrained to passoutward around the margins of the washers 32 into the channels 33, orthe like, through which they flow, in cooling contact with the cap ends31, to the vents 34. Their heat and pressure are now so reduced ordissipated that no danger attends their escape.

To remove the fuse strip it is merely necessary to. unscrew the ferrules12, carrying the. washers 32, swing the shutters 17 and 18 outward tothe position indicated in dotted lines in Fig. 3, whereupon the burntfuse 4strip ends may be removed through the openings 19 in the bushing,a new fuse strip inserted therethrough, the shutters swung back toclosure position and the ferrules again adjusted. It will be noted thatthere are no loose washers or parts apt to be lost or misplaced, theShutters 17 and 18 being permanently -attached to the diaphragms 13 and14, and the washers 32 Y being -permanently attached to the ferrules 12.

The provision of the exposed indicator 28 on the fuse renders inspectionof the latter simple, and insures the use of a fuse strip of propercapacity for the casing. 'While it is intended that within a givenrange, fuses of diiierent capacity may be used with a single casingconstruction, the

. variation of the thickness of the fuse strips is not sufiicient torender the seal at the grooves 26, 27 ineffective. Were it4 attempted,however, to insert a fuse strip of greater capacity than that for whichthe cas- -ing is designed, its greater thickness would skilled in theart, and I do not limit my invention to the precise structureillustrated and above described.

I claim- Y 1. A cartridge fuse having a detachable end closure cap, andpermanently secured therein in loose relation a gas-deilecting andheat-absorbing washer.

2. A cartridge fuse having a detachable los iis

izo

end cap, and permanently secured within the same in loose relation akgas-deflecting and heat-absorbing washer affording a vent passagebetween the outer face of the washer and the inner` face ofthe end cap,said washer being of less diameter than the internal diameter of thecap.

5. In a cartridge fuse, a detachable `end cap, in combination with awasher carried thereby on its inner face, and a boss on the inner faceof the washer for making contact with the end of a fuse strip.

6. In a cartridge fuse, a detachable screw cap, and-carried thereby afuse contacting member freely swiveling in the cap.

7. A cartridge fuse having a substantially closed fuse chamber, andmeans for supporting in exposed (position at one end thereof thebent-over en of a fuse strip, in combination with a detachable end cap,and loosely carried thereby a contactfmember adapted to engage the endof the fuse strip.

8. A cartridge fuse having a substantially closed fuse chamber, andmeans for supporting in exposed position at one end thereof v thebent-over end of a fuse strip, in combina-fe `tion with a detachablefend cap, and freely,

carried thereby a venting contact member 'the latter and the cap.

adapted to engage the end of the fuse strip. 9. A cartridge fuse havinga substantially closed fuse chamber, and means for supporting in exposedposition at one end thereof,4 the bent-over end of a fuse strip, incombination with a detachable end cap, a washer carried thereby withinthe cap, and a boss on the inner face of said washer adapted to spacethe latter from the end 'of the fuse chamber to afford an expansionchamber for gases escaping from the fuse chamber on the blowing of thefuse.

10. A cartridgey fuse having a substany tially closed fuse chamber andmeans for supporting at one yend thereof the bentfover end of a. fusestrip, in lcombination witha detachable end cap, a washer carried bysaid cap and lying within the same, and a boss on the inner face of saidwasher to engage the bent-over end ofthe fusestrip and serving to spacethe washer from theend of the fuse chamber to yafford a gas expansionchamber, together with means affording a gas escape passage around theperiphery of the washer and between -theouter face of 11. A cartridgefuse having a tubular casing of insulating material, a metallic Ibushing secured at the end of the casing,

said bushing having an external screw thread and a reduced area at theouter end of said bushing beyond the screw thread, in combination with adetachable screw cap adapted to engage the threaded area of the bushing,and having a snug fit with the reduced end of the bushing to prevent theescape of kgas thereby to the threaded area.

In testimony whereof I have signed my name to this specification.

ARCHIBALD GRIEVE.

